System and Method for Information Delivery with Multiple Point Transmission

ABSTRACT

A system and method for information delivery with multiple point transmission are provided. A method for detecting lost packets is provided. The method includes initiating a timer for a received packet at a receiving transmission point, where the timer is set according to a time value associated with the received packet. The method also includes determining that a delivery of the received packet has failed according to the timer elapsing, and transmitting a lost packet report to a primary transmission point that distributed the received packet to the receiving transmission point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/255,870, entitled “System and Method for Information Delivery withMultiple Point Transmission,” filed on Sep. 2, 2016, which is acontinuation of U.S. patent application Ser. No. 13/269,485, entitled“System and Method for Information Delivery with Multiple PointTransmission,” filed on Oct. 7, 2011, which applications are herebyincorporated herein by reference

TECHNICAL FIELD

The present invention relates generally to digital communications, andmore particularly to a system and method for information delivery withmultiple point transmission.

BACKGROUND

In order to achieve better channel utilization and increase overallperformance, multiple transmission and multiple reception antennas (alsocommonly referred to as multiple input, multiple output (MIMO)) at bothenhanced Node B (eNB) (or base station (BS), Node B (NB), communicationscontroller, and so forth) and User Equipment (UE) (or mobile station(MS), terminal, user, subscriber, subscriber equipment, and so on) areconsidered.

An extension to MIMO makes use of multiple transmission points (each ofwhich may be a set of geographically co-located transmit antennas) totransmit to a single UE or a group of UE. The transmissions from themultiple transmission points may occur at different times so that over agiven time window, the UE (or the group of UE) will receivetransmissions from all of the multiple transmission points. Thisoperating mode may often be referred to as multiple point transmission.As an example, at a first time, a first transmission point may transmitto a UE, at a second time, a second transmission point may transmit tothe UE, and so on.

Coordinated multiple point (CoMP) transmission is one form of multiplepoint transmission, wherein the transmissions made by the multipletransmission points are coordinated so that the UE or the group of UEmay be able to either combine the transmissions made by the multipletransmission points or avoid interference to improve overallperformance. A transmission point may be an eNB, a part of an eNB (i.e.,a cell), a remote radio head (RRH) connected to an eNB, or so on. It isnoted that sectors of the same site, e.g., an eNB, correspond todifferent transmission points. Similarly, CoMP reception involves thereception of a transmitted signal(s) at multiple geographicallyseparated reception points.

CoMP transmission and reception is being considered for inclusion innext generation wireless communications systems, such as in ThirdGeneration Partnership Project (3GPP) Long Term Evolution (LTE) Advancedstandards compliant communications systems, as a tool to improve thecoverage of high data rates, cell-edge throughput, and/or to increaseoverall communications system throughput in both high load and low loadscenarios.

SUMMARY

These technical advantages are generally achieved by embodiments of thepresent invention which provides a system and method for informationdelivery with multiple point transmission.

In accordance with an example embodiment of the present invention, amethod for detecting lost packets is provided. The method includesinitiating a timer for a received packet at a receiving transmissionpoint, where the timer is set according to a time value associated withthe received packet. The method also includes determining that adelivery of the received packet has failed according to the timerelapsing, and transmitting a lost packet report to a primarytransmission point that distributed the received packet to the receivingtransmission point.

In accordance with another example embodiment of the present invention,a method for transmitting information by a primary transmission point isprovided. The method includes determining a distribution for allocatingpackets in a plurality of packets to N transmission points in a multiplepoint cooperating set, where N is an integer value greater than or equalto two, where the primary transmission point is one of the Ntransmission points. The method also includes allocating the packets inthe plurality of packets to the N transmission points for transmissionto a user equipment in accordance with the distribution, where theplurality of packets to be transmitted by the N transmission pointsbelong to a single radio bearer. The method further includes sending theallocated packets to the N transmission points, and transmitting primarypackets allocated to the primary transmission point to the userequipment.

In accordance with another example embodiment of the present invention,a primary transmission point is provided. The primary transmission pointincludes a processor, and a transmitter coupled to the processor. Theprocessor determines a distribution for allocating packets in aplurality of packets to N transmission points in a multiple pointcooperating set, where N is an integer value greater than or equal totwo, where the primary transmission point is one of the N transmissionpoints. The processor also allocates the packets in the plurality ofpackets to the N transmission points for transmission to a userequipment in accordance with the distribution, where the plurality ofpackets to be transmitted by the N transmission points belong to asingle radio bearer. The transmitter sends the allocated packets to theN transmission points, and transmits primary packets allocated to theprimary transmission point to the user equipment.

In accordance with another example embodiment of the present invention,a method for operating a user equipment is provided. The method includesordering the packets of a single radio bearer received from multipletransmission points according to a sequencing number associated witheach packet.

One advantage of an embodiment is that multiple point transmission issupported without stringent timing requirements, which may makeimplementation difficult and/or expensive.

A further advantage of an embodiment is that techniques for radio bearerestablishment and/or modification allow for implementation of multiplepoints transmission without requiring significant hardware and/orsoftware changes, which may help to simplify implementation and keepcosts low.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates an example communications system according to exampleembodiments described herein;

FIG. 2 illustrates an example communications system, wherein a transportof packets is highlighted according to example embodiments describedherein;

FIG. 3 illustrates an example portion of a protocol stack used in datatransmission over a radio bearer according to example embodimentsdescribed herein;

FIG. 4 illustrates an example communications system, wherein DL CoMPtransmission is taking place for some of the UEs operating in a coveragearea of communications system according to example embodiments describedherein;

FIG. 5 illustrates an example logical view of a communications system,highlighting a CoMP cooperating set and a CoMP controller according toexample embodiments described herein;

FIG. 6 illustrates an example diagram of a radio bearer split accordingto example embodiments described herein;

FIG. 7a illustrates an example communications system, wherein a CoMPcooperating set is highlighted according to example embodimentsdescribed herein;

FIG. 7b illustrates an example communications system, wherein a settingup or configuration of a radio bearer is highlighted according toexample embodiments described herein;

FIG. 7c illustrates an example flow diagram of primary transmissionpoint operations in transmitting packets to a UE over a single radiobearer according to example embodiments described herein;

FIG. 8 illustrates an example message flow diagram for setting up ormodifying a radio bearer for CoMP transmission according to exampleembodiments described herein;

FIG. 9 illustrates an example flow diagram of operations in setting upor modifying a radio bearer for CoMP transmission according to exampleembodiments described herein;

FIG. 10a illustrates an example flow diagram of UE operations in settingup or modifying a radio bearer for CoMP transmission according toexample embodiments described herein;

FIG. 10b illustrates an example flow diagram of primary transmissionpoint operations in setting up or modifying a radio bearer for CoMPtransmission according to example embodiments described herein;

FIG. 10c illustrates an example flow diagram of secondary transmissionpoint operations in setting up or modifying a radio bearer for CoMPtransmission according to example embodiments described herein;

FIG. 10d illustrates an example flow diagram of CoMP controlleroperations in setting up or modifying a radio bearer for CoMPtransmission according to example embodiments described herein;

FIG. 11 illustrates an example flow diagram of operations in re-orderingof packets according to example embodiments described herein;

FIG. 12a illustrates an example flow diagram of operations in an RLCentity as the RLC entity performs network assisted lost packetmitigation according to example embodiments described herein;

FIG. 12b illustrates an example flow diagram of operations in a PDCPentity as the PDCP entity performs network assisted lost packetmitigation according to example embodiments described herein;

FIG. 12c illustrates an example flow diagram of operations in UEassisted lost packet mitigation according to example embodimentsdescribed herein;

FIG. 13 provides an example illustration of a transmission pointaccording to example embodiments described herein; and

FIG. 14 provides an example illustration of a CoMP controller accordingto example embodiments described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The operating of the current example embodiments and the structurethereof are discussed in detail below. It should be appreciated,however, that the present invention provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificstructures of the invention and ways to operate the invention, and donot limit the scope of the invention.

One embodiment of the invention relates to multiple point transmissionsfrom multiple transmission points over a single radio bearer. Eachtransmission point includes an RLC entity, while one transmission pointalso includes a PDCP entity. At a multi-point controller, decisions tomodify an existing multiple point configuration is made based on systemconditions, resulting in the addition of an additional transmissionpoint, the removal of an existing transmission point, the addition of aradio bearer, moving an existing transmission point, and so on.

The present invention will be described with respect to exampleembodiments in a specific context, namely a 3GPP LTE-Advanced compliantcommunications system. The invention may also be applied, however, toother standards compliant communications systems, such as IEEE 802.16m,WiMAX, and so on, as well as non-standards compliant communicationssystems that support multiple point transmission.

FIG. 1 illustrates a communications system 100. Communications system100 includes an eNB 105 serving UE no and UE 112. eNB 105 (as well asother eNBs and their associated cells) provides an air interface forcommunications system 100 and is commonly referred to as an EnhancedUniversal Mobile Telecommunications System (UMTS) Terrestrial RadioAccess Network (E-UTRAN). A connection may be setup from a UE througheNB 105, a serving gateway (serving GW) 115, and a packet data networkgateway (PDN GW) 120 to an operator's Internet Protocol (IP) servicesnetwork 125.

While it is understood that communications systems may employ multipleeNBs capable of communicating with a number of UEs, only one eNB, twoUEs, one serving GW, and one PDN GW are illustrated for simplicity.

FIG. 2 illustrates a communications system 200, wherein a transport ofpackets is highlighted. The transport of packets from PDN GW 220 to UE205 may be organized through Evolved Packet System (EPS) bearers, whichmay be radio or wireline bearers. Between PDN GW 220 and serving GW 215,an S5/S8 bearer supports the transport of packets, while between servingGW 215 and eNB 210, an S1 bearer supports the transport of packets. Aradio bearer supports the transport of packets between eNB 210 and UE205. Traffic flows may be aggregated and then sent over respectivebearers to their intended destination.

FIG. 3 illustrates a portion of a protocol stack 300 used in datatransmission over a radio bearer. Protocol stack 300 illustrates amedium access control (MAC) layer 305, a radio link control (RLC) layer310, and a packet data convergence control (PDCP) layer 315. In currentgeneration 3GPP LTE communications systems (e.g., 3GPP LTE Release-8,Release-9, and Release-10), each radio bearer of a UE is associated withone PDCP entity, and each PDCP entity is associated with one RLC entityfor DL transmissions.

FIG. 4 illustrates a communications system 400, wherein DL multiplepoint transmission (e.g., CoMP transmission) is taking place for some ofthe UEs operating in a coverage area of communications system 400.

Although the discussion of FIG. 4 focuses on eNBs as communicationscontrollers. Other types of communications controllers may be used inplace of or in conjunction with eNBs. For example, BSs, Low Power Nodes(LPN), femto cells, pico cells, and so on, may be used as replacementsof or in conjunction with eNBs. Therefore, the discussion of eNBs shouldnot be construed as being limiting to either the scope or the spirit ofthe example embodiments.

Furthermore, the discussion presented herein focuses on CoMPtransmission. However, the example embodiments presented here are alsooperable with a more general form of CoMP transmission, i.e., multiplepoint transmission. Therefore, the discussion of CoMP transmissionshould not be construed as being limiting to either the scope or thespirit of the example embodiments.

Communications system 400 includes a number of eNBs, such as eNB 405,eNB 407, and eNB 409, and a number of remote radio heads (RRH), such asRRH 410, RRH 412, RRH 414, RRH 416, RRH 418, and RRH 420. RRHs may alsobe referred to as remote radio units (RRU). Communications system 400also includes a number of UEs, such as UE 425, UE 427, and UE 429. TheUEs may be served by one or more eNBs, one or more RRHs, or acombination of eNBs and RRHs. The eNBs may allocate a portion of theirbandwidth to the RRHs in order to help improve coverage, performance,and so forth.

As shown in FIG. 4, UE 425 may be served by RRH 410 and RRH 412, as wellas eNB 405. While UE 427 may be served by RRH 414, RRH 416, and RRH 418.UE 429 may be served by RRHs controlled by different eNBs, such as RRH414 and RRH 418 (controlled by eNB 409) and RRH 420 (controlled by eNB407).

A transmission point within a DL serving set may be referred to as aprimary transmission point (or simply primary or primary point) and theremaining transmission point(s) in the DL serving set may be referred toas secondary transmission point(s) (or simply secondary, secondarypoint, secondaries, or secondary points). The primary transmission pointmay be considered to be a controlling transmission point, responsiblefor assigning identification information, distributing DL data to thesecondary transmission points, and so forth.

Transmission points, such as eNBs, cells of eNBs, RRHs, and so forth,involved in a multiple point operation form a multiple point cooperatingset. Furthermore, when the transmission points are involved in CoMPoperation, the transmission points form a CoMP cooperating set. Thetransmission points may be associated with a single cell or differentcells. A network pre-connected, UE assisted approach can be taken toconfigure a CoMP cooperating set for a UE. Based on the condition ofchannels between a UE and a set of transmission points, which arepre-connected to allow inter-transmission point communications, a CoMPcooperating set may be dynamically setup for an application's databearer to include transmission points with congenial channelcharacteristics.

Among members of a CoMP cooperating set, the primary transmission pointmay be responsible for UE specific signaling, including paging. Othermembers of the CoMP cooperating set may contribute data transmission.

FIG. 5 illustrates a logical view of a communications system 500,highlighting a CoMP cooperating set and a CoMP controller. As shown inFIG. 5, a CoMP controller 505 may be viewed as a centralized controlpoint with a CoMP cooperating set 510. CoMP controller 505 may provide aunified control for setting up, configuring CoMP transmissions for radiobearers, coordinating the operation of multiple transmission points withCoMP cooperating set 510, and so on. CoMP controller 505 may be realizedas a separate physical entity connecting all (existing as well aspotential) transmission points of CoMP cooperating set 510.Alternatively, CoMP controller 505 may be a logical function co-locatedwithin an existing network entity, such as an eNB.

Communications system 500 also includes a mobility management entity(MME) pool 515 that may be responsible for providing MMEs that may beused for radio bearer activation and/or deactivation, as well as UEtracking and paging procedures. MME pool 515 may include a number ofMMEs that may be assigned to a CoMP controller (such as CoMP controller505) when the CoMP controller has a need for radio bearer management,and so on. Assigned MMEs may be released once they are no longer needed.

Communications system 500 also includes a serving gateway (S-GW) pool520 that may be responsible for providing S-GWs that may be used aspoint of entry and/or exit for traffic to or from a UE. S-GW pool 520may include a number of S-GWs that may be assigned when needed andreleased when no longer needed.

According to an example embodiment, a single radio bearer may beassociated with multiple RLC entities at multiple transmission points toallow for the transmission of data from the single radio bearer usingthe multiple transmission points. The use of data splitting between asingle PDCP entity and multiple RLC entities allows a CoMP transmissionto be setup and configured for individual radio bearers so that the datapackets of one radio bearer may be transmitted over multipletransmission points (e.g., eNBs, cells, RRHs, and so on).

FIG. 6 illustrates a diagram 600 of a radio bearer split. As shown inFIG. 6, data from higher network layers, such as a service data unit(SDU) of a third layer of a multi-layer network protocol stack (forexample, the seven-layer Open Systems Interconnection (OSI) protocols),may arrive at a PDCP entity 605. PDCP entity 605 may perform operationssuch as IP header compression and/or decompression, sequence numbermaintenance, ciphering, and so forth, to produce a PDCP Protocol DataUnit (PDU).

The PDCP PDUs may be provided to a data splitting interface 610 that maysplit the PDCP PDUs into two or more PDCP PDU streams. An actual numberof PDCP PDU streams may be dependent on a number of separate RLCentities. As an example, if there are three separate RLC entities, thenthe PDCP PDUs may be split into three PDCP PDU streams.

Although shown as a single entity, data splitting interface 610 may be adistributed entity present in each transmission point in a CoMPcooperating set. As an example, a primary transmission point may includean instantiation of data splitting interface 610 to distribute the PDCPPDUs to the various transmission points, while each of the transmissionpoints (including the primary transmission point) may include aninstantiation of data splitting interface 610 to assist in processingthe distributed PDCP PDUs.

A distribution of the split of the PDCP PDUs to the PDCP PDU streams maybe dependent on factors such as available resources at transmissionpoints corresponding to each RLC entity, a load at the transmissionpoints, capability of the transmission points, channel conditions at thetransmission points, and so forth. As an illustrative example, if thetwo transmission points are relatively equal in terms of availableresources, capability, channel condition, and so on, then the PDCP PDUsmay be split into two relatively equal PDCP PDU streams, whereinrelatively equal implies that over time, approximately ½ of the PDCPPDUs will be allocated to each of the two transmission points. However,if one of the transmission points is significantly more capable orsignificantly less capable, then the allocation of the PDCP PDUs to thatparticular transmission point may be adjusted accordingly.

According to an example embodiment, a nature of the split of the PDCPPDUs, such as the distribution, a duration of the split, how to handlelost PDUs, redistribution of the PDUs after one or more PDUs have beenlost, and so forth, may be performed by a CoMP controller and providedto a primary transmission point or by the primary transmission point orby a combination of the CoMP controller and the primary transmissionpoint.

According to an example embodiment, measurements of the performance ofthe transmission points may be performed to allow for the dynamicadjustment of the allocation of the PDCP PDUs to each of thetransmission points. As an example, if transmissions from onetransmission point are prone to failure (e.g., being marked as lost),then a number of PDCP PDUs being allocated to the transmission point maybe reduced, while PDCP PDUs being allocated to the other transmissionpoint may be increased.

Although the discussion focuses on two transmission points, a CoMPcooperating set may include any number of transmission points greaterthan two, such as three, four, five, and so on. Therefore, thediscussion of two transmission points should not be construed as beinglimiting to either the spirit or the scope of the example embodiments.

The PDCP PDU streams may be provided to separate RLC entities, such asRLC entity 615 and RLC entity 617. The separate RLC entities may resideon geographically separated transmission points. As an example, RLCentity 615 may reside on a cell, while RLC entity 617 may reside onanother cell, which may or may not be part of the same eNB. Atransmission point where PDCP entity 605 resides may provide the PDCPPDU streams to the separate transmission points.

A data splitting interface, such as data splitting interface 610, may beimplemented as a separate interface between a PDCP entity (such as PDCPentity 605) and a RLC entity (such as RLC entity 615 and/or RLC entity617). Alternatively, the data splitting interface may be implementedwithin a PDCP entity or a RLC entity. Alternatively, a portion of thedata splitting interface may be implemented within a PDCP entity and aportion of the data splitting interface may be implemented within a RLCentity.

According to an example embodiment, one transmission point may includeboth a PDCP entity (such as PDCP entity 605) and an RLC entity (such asRLC entity 615 or RLC entity 617). Generally, such a transmission pointmay serve as a primary transmission point of a CoMP cooperating set.

The transmission points where the RLC entities reside may then providethe PDCP PDUs in the PDCP PDU streams to the UE.

According to an example embodiment, in order for a UE to know how asingle radio bearer is provisioned with multiple RLC entities, a RadioResource Control (RRC) message may be sent to the UE. The RRC messagemay include pairings of transmission point identity and RLCconfiguration information for each transmission point involved with thesingle radio bearer. As an example, if the single radio bearer isprovisioned into three RLC entities, the RRC message may contain threepairings of transmission point identity and RLC configurationinformation, one per RLC entity.

FIG. 7a illustrates a communications system 700, wherein a CoMPcooperating set is highlighted. Communications system 700 includes aprimary transmission point 705, which may be an eNB, a cell, a RRH, orso on, and a secondary transmission point 710, which may be an eNB, acell, a RRH, or so on. Both primary transmission point 705 and secondarytransmission point 710 may be transmitting to a UE 715.

As discussed previously, in order to support the splitting of a singleradio bearer, both primary transmission point 705 and secondarytransmission point 710 may each include an RLC entity. Primarytransmission point 705 may also include a PDCP entity, while secondarytransmission point 710 may not (at least with respect to the singleradio bearer used in the CoMP cooperating set involving UE 715).

As shown in FIG. 7 a, a single radio bearer is shared between the twotransmission points, with a branch of radio bearer between primarytransmission point 705 and UE 715 being labeled as sub radio bearer 1(A)and a branch of radio bearer between secondary transmission point 710and UE 715 being labeled as sub radio bearer 1(B). In order forsecondary transmission point 710 to transmit information to UE 715,primary transmission point 705 may provide data, information, and so on,to secondary transmission point 710 over a backhaul link, for example.

FIG. 7b illustrates a communications system 750, wherein a setting up orconfiguration of a radio bearer is highlighted. Communications system750 includes a primary transmission point 755 and a secondarytransmission point 760. Both primary transmission point 755 andsecondary transmission point 760 may be transmitting to UE 765.

As shown in FIG. 7 b, primary transmission point 755 and UE 765 mayexchange messages to inform UE 765 of changes to its CoMP cooperatingset, and primary transmission point 755 and secondary transmission point760 may exchange messages through a CoMP controller, for example, tosetup or configure the splitting of a radio bearer (shown as radiobearer X in FIG. 7b ). Once the splitting of radio bearer X has beensetup or configured, both primary transmission point 755 and secondarytransmission point 760 may transmit to UE 765 over radio bearer X.

FIG. 7c illustrates a flow diagram of primary transmission pointoperations 775 in transmitting packets to a UE over a single radiobearer. Primary transmission point operations 775 may be indicative ofoperations occurring in a primary transmission point as it providespackets to other transmission points in a CoMP cooperating set fortransmission to a UE.

Primary transmission point operations 775 may begin with the primarytransmission point receiving packets to be transmitted to the UE (block780). According to an example embodiment, the primary transmission pointmay receive the packets from a serving gateway that couples the primarytransmission point to a source of the packets.

The primary transmission point may assign (block 782) and then send eachof the packets that it receives from the serving gateway to one of Ntransmission points in the CoMP cooperating set (block 784). It is notedthat the primary transmission point may be considered to be one of the Ntransmission points. According to an example embodiment, the primarytransmission point may assign (e.g., distribute) the packets to the Ntransmission points based on a desired distribution. As an example, ifeach transmission point is to receive the same number of packets, thenthe primary transmission point may send 1/N-th of the total number ofpackets to each transmission point. Alternatively, the primarytransmission point may send more packets to transmission points that aremore capable, have better quality channels to the UE, have lower load,and so forth. Similarly, transmission points that are less capable, havelower quality channels to the UE, have greater load, and so on, may besent fewer packets.

According to an example embodiment, the primary transmission point maydetermine the desired distribution for distributing the packets to the Ntransmission points. Additionally, the primary transmission point maydetermine other aspects of the CoMP transmission, such as a duration ofthe split, how to handle lost PDUs, redistribution of the PDUs after oneor more PDUs have been lost, and so forth. Alternatively, a CoMPcontroller may determine the desired distribution, as well as the otheraspects of the CoMP transmission, and provide the information to theprimary transmission point. Alternatively, both the primary transmissionpoint and the CoMP controller may cooperate and determine the desireddistribution, as well as the other aspects of the CoMP transmission.

The primary transmission point (and the other transmission points in theCoMP cooperation set) may transmit the packets to the UE (block 786).The transmission points in the CoMP cooperation set may or may not needto send the packets in synchrony.

FIG. 8 illustrates a message flow diagram 800 for setting up ormodifying CoMP transmission configuration. Message flow diagram 800includes messages exchanged between a UE 805, a primary transmissionpoint 810, a secondary transmission point 815, a CoMP controller 820,and an S-GW 825. Message flow diagram 800 illustrates messages exchangedin a setting up or modifying a CoMP transmission configuration, such asa radio bearer transmission configuration therein, where the setting upor modifying the CoMP transmission configuration may include:

1) Adding a secondary transmission point to the CoMP transmissionconfiguration, and configuring its RLC entity and related data splittinginterface with desired Quality of Service (QoS) and data deliverycharacteristics;

2) Removing a secondary transmission point from the CoMP transmissionconfiguration;

3) Adding a radio bearer to a CoMP transmission configuration; and

4) Switching a component RLC entity from a first secondary transmissionpoint to a second secondary transmission point in a CoMP transmissionconfiguration, which may be accomplished by adding the second secondarytransmission point and then removing the first secondary transmissionpoint, for example.

For discussion purposes, consider a situation wherein UE 805 is alreadyparticipating in communications through primary transmission point 810and serving gateway 825 (shown as event 830). UE 805 may or may not beparticipating in multiple point transmission, such as CoMP transmission,with primary transmission point 810 (and at least one secondarytransmission point not shown in FIG. 8).

Then, at a specified time, upon receipt of an instruction from primarytransmission point 810, an elapsing of a timer, or so on, UE 805 maymake a measurement of channel conditions and report the measurement ofthe channel conditions to primary transmission point 810, which may thenprovide the measurement of channel conditions to CoMP controller 820(shown as event 832). The measurement of channel conditions may includemeasurements of signal levels, interference levels, signal tointerference plus noise ratios, signal to noise ratios, and so forth. Inaddition to measuring its own channel conditions, UE 805 may alsomeasure channel conditions of nearby eNBs, cells, relay nodes (RNs),RRHs, and so on, and report the measurements to primary transmissionpoint 810. In general, UE 805 may be providing a picture of itsoperating condition through the measurement of the channel conditions.

According to an example embodiment, the setting up or modifying of aCoMP transmission configuration, which may include setting up ormodifying a radio bearer, may be based on measurement of channelconditions, as well as other operating conditions, which may includecommunications system traffic patterns and/or load, traffic amountand/or priority, UE priority, UE service history, and so on.

Based on the measurement of channel conditions made by UE 805 (andpotentially as well as measurements from other UEs), CoMP controller 820may determine an appropriate CoMP transmission configuration (e.g., aCoMP transmission mode) to be used, such as, settings of a radio bearerto be used in CoMP transmission, and so on. Settings of the radio bearermay include which transmission points (e.g., primary transmission pointand one or more secondary transmission points) may be involved incarrying the radio bearer, as well as QoS and/or Radio ResourceManagement (RRM) parameters of the radio bearer for the involvedtransmission points.

If the measurement of the channel conditions warrant a change in theCoMP transmission configuration, such as adding a transmission point tothe CoMP transmission configuration, removing a transmission point fromthe CoMP transmission configuration, adding a new radio bearer, moving atransmission point, or so on, CoMP controller 820 may send a CoMPConfiguration Request message to a transmission point involved (e.g.,secondary transmission point 815) to determine if the transmission pointinvolved is amenable to the change in the CoMP transmissionconfiguration (shown as event 834). As an illustrative example, thetransmission point involved (secondary transmission point 815) mayalready be a member of the CoMP cooperating set of UE 805, and CoMPcontroller 820 may determine that the measurement of the channelconditions warrant that the transmission point involved be removed.Alternatively, the transmission point involved may not be a member ofthe CoMP cooperating set of UE 805, and CoMP controller 820 maydetermine that the measurement of the channel conditions warrant thatthe transmission point involved be added to the CoMP cooperating set.

According to an example embodiment, the CoMP Configuration Requestmessage may include the QoS and/or RRM parameters as determined by CoMPcontroller 820. The QoS and/or RRM parameters may include QoS ClassIndex (QCI), Allocation and Retention Priority (ARP), bit rateinformation (what is a guaranteed bit rate and what is a best effort bitrate, as examples), possible radio resource partitioning (in time and/orfrequency domain, for example), and so on.

For discussion purposes, assume that the QoS and/or RRM parametersprovided by CoMP controller 820 are acceptable to the transmission pointinvolved. If the QoS and/or RRM parameters as provided by CoMPcontroller 820 in the CoMP Configuration Request message are acceptableto the transmission point involved (secondary transmission point 815),then the transmission point involved may respond to the CoMPConfiguration Request message with a CoMP Configuration Accept message(shown as event 836). The CoMP Configuration Accept message may includean identifier assigned to UE 805 in a context of the transmission pointinvolved.

If the QoS and/or RRM parameters provided by CoMP controller 820 are notacceptable to the transmission point involved, then the transmissionpoint involved may respond negatively to the CoMP Configuration Requestmessage. The CoMP controller 820 may need to adjust the QoS and/or RRMparameters or abort its changes to the CoMP transmission configuration.

Although message flow diagram 800 illustrates CoMP transmissioninvolving a single secondary transmission point, the example embodimentspresented herein may be extended to support multiple secondarytransmission points by those of ordinary skill in the art of the exampleembodiments. Therefore, the discussion of a single secondarytransmission point should not be construed as being limiting to eitherthe scope or the spirit of the example embodiments.

CoMP controller 820 may then send a CoMP Radio Bearer ConfigurationRequest message to primary transmission point 810 to inform primarytransmission point 810 that the CoMP transmission configuration for aspecified radio bearer is being changed (shown as event 838). The CoMPRadio Bearer Configuration Request message may include identifyinginformation for the specified radio bearer, identifying information foran associated Enhanced Packet System (EPS) bearer, identifyinginformation for a transmission point that will carry the specified radiobearer (e.g., whether the specified radio bearer is to be added toprimary transmission point 810 or secondary transmission point 815),identifying information for UE 805 in the transmission that will becarrying the specified radio bearer, configuration information on howthe specified radio bearer will be transmitted in the transmission pointinvolved (secondary transmission point 815) (i.e., whether or not datafor the specified radio bearer is to be split between primarytransmission point 810 and secondary transmission point 815, and if thedata is to be split, what new QoS control parameters, such as QCI, ARP,bit rate, and so forth, are to be used in primary transmission point810), how in-order delivery of PDCP packets should be performed tocombine data from RLC entities corresponding to different transmissionpoints, how data retransmissions should be handled should a PDCP packettransmission fail, and so forth.

Primary transmission point 810 may inform UE 805 of changes to the CoMPtransmission configuration with a CoMP Configuration Request message(shown as event 840). The CoMP Configuration Request message mayidentify the transmission points involved in the CoMP transmission. TheCoMP Configuration Request message may also identify associated radiobearer and EPS bearer, the identity of UE 805 with the transmissionpoints, associated radio bearer configuration parameters, and so on. Theconfiguration parameters for the associated radio bearer may include howin-order delivery of PDCP packets should be performed to combine datafrom the RLC entities from the different transmission points, how UE 805should respond to missing PDCP packets, and so forth.

UE 805, from the CoMP Configuration Request message from primarytransmission point 810, knows that it may be sent data packets from theassociated radio and EPS bearers using specified PDCP and RLCparameters. UE 805 may also make use of information regarding in-orderdelivery of PDCP packets to combine data from the RLC entities ofdifferent transmission points of the radio bearer. UE 805 may alsoprovide status reports about PDCP packets if it is required to do so. UE805 may respond positively to the CoMP Configuration Request messagewith a CoMP Configuration Complete message indicating that it is readyto receive the transmissions (shown as event 842).

After receiving the positive response from UE 805 (i.e., the CoMPConfiguration Complete message), primary transmission point 810 mayrespond positively to CoMP controller 820 with a CoMP Radio BearerConfiguration Response message (shown as event 844).

CoMP controller 820 may send to secondary transmission point 815 a CoMPRadio Bearer Configuration Request message to make changes to the CoMPtransmission configuration (shown as event 846). The CoMP Radio BearerConfiguration Request message may include QoS and/or RRM parameters forthe radio bearer. The QoS and/or RRM parameters may includeconfiguration information for RLC entity and MAC entity located atsecondary transmission point 815. Secondary transmission point 815 mayalso be provided information regarding if it should provide reports ofpackets with failed delivery attempts and how to do so.

Secondary transmission point 815 may respond positively to the CoMPRadio Bearer Configuration Request message with a CoMP Radio BearerConfiguration Response message (shown as event 848). The CoMP RadioBearer Configuration Response message may be sent by secondarytransmission point 815 after it has stored the received parameters(e.g., the QoS and/or RRM parameters) and/or configured associated RLCand MAC entities.

CoMP controller 820 may inform primary transmission point 810 thatchanges to the CoMP transmission configuration has been established forUE 805 in a CoMP Radio Bearer Configuration Request message (shown asevent 850). Primary transmission point 810 may receive packets for theradio bearer from serving gateway 825 (shown as event 852) and pass someof the packets, based on a distribution, for example, to secondarytransmission point 815 through a data splitting interface (shown asevent 854). Packets of the radio bearer may be transmitted to UE 805from both primary transmission point 810 (shown as event 856) andsecondary transmission point 815 (shown as event 858).

FIG. 9 illustrates a flow diagram of operations 900 in setting up ormodifying a CoMP transmission configuration, such as radio bearertransmission configuration therein. Operations 900 may be indicative ofoperations occurring as a CoMP transmission configuration, e.g., a radiobearer, is set up or modified.

Operations 900 may begin with a measurement of channel conditions (block905). The measurement of channel conditions may be made by a UE and maybe a measurement of channel conditions of channel to or from the UE. Thechannel conditions may also be for transmission points that are near ordetectable by the UE.

The measurement of channel conditions may be used to determine ifchanges in an existing CoMP transmission configuration are warranted(block 910). If the measurement of channel conditions does not warrant achange in the existing CoMP transmission configuration, then theexisting CoMP transmission configuration may continue as configured(block 915).

However, if the measurement of channel conditions does warrant a changein the existing CoMP transmission configuration, then the CoMPtransmission configuration, e.g., the radio bearer transmissionconfiguration, may be modified (block 920). The change to the existingCoMP transmission configuration may be implemented (or reconfigured)using an exchange of messages (block 925). Implementation of the changeto the existing CoMP transmission configuration may include informingthe participants of the CoMP transmission of the changes to the CoMPtransmission configuration. Once the participants of the CoMPtransmission have been informed and the CoMP transmission configurationhas been changed, the new CoMP transmission may commence (block 930).

FIG. 10a illustrates a flow diagram of UE operations 1000 in setting upor modifying a CoMP transmission configuration. UE operations 1000 maybe indicative of operations occurring in a UE, such as UE 805, as the UEparticipates in setting up or modifying a CoMP transmissionconfiguration, such as radio bearer transmission configuration.

UE operations 1000 may begin with the UE measuring and reporting channelconditions (block 1005). The UE may measure and report channelconditions for itself, as well as for transmission points that are inclose proximity to the UE or are detectable by the UE. The UE may reportthe measured channel conditions to a primary transmission point of theUE.

The UE may receive a CoMP Configuration Request message from its primarytransmission point (block 1007). The CoMP Configuration Request messagemay be used to inform the UE of the changes to the CoMP transmissionconfiguration, such as the addition of a transmission point, thedeletion of a transmission point, the addition of a radio bearer, thedeletion of a radio bearer, and so on. The CoMP Configuration Requestmessage may identify the transmission points involved in the CoMPtransmission. The CoMP Configuration Request message may also identifyassociated radio bearer and EPS bearer, the identity of the UE with thetransmission points, associated radio bearer configuration parameters,and so on. The configuration parameters for the associated radio bearermay include how in-order delivery of PDCP packets should be performed tocombine data from the RLC entities from the different transmissionpoints, how UE 805 should respond to missing PDCP packets, and so forth.The UE may respond to the CoMP Configuration Request message with a CoMPConfiguration Complete message.

The UE may receive transmissions from transmission points that areparticipating in CoMP transmission with the UE (block 1009). Thetransmissions may be from multiple transmission points, but associatedwith a single radio bearer.

FIG. 10b illustrates a flow diagram of primary transmission pointoperations 1025 in setting up or modifying a CoMP transmissionconfiguration. Primary transmission point operations 1025 may beindicative of operations occurring in a primary transmission point, suchas primary transmission point 810, as the primary transmission pointparticipates in setting up or modifying a CoMP transmissionconfiguration, such as radio bearer transmission configuration.

Primary transmission point operations 1025 may begin with the primarytransmission point forwarding measurements of channel conditionsreceived from a UE to a CoMP controller (block 1030).

The primary transmission point may receive a CoMP Radio BearerConfiguration Request message to inform the primary transmission pointthat the CoMP transmission configuration for a specified radio bearer isbeing changed (block 1032). The CoMP Radio Bearer Configuration Requestmessage may include identifying information for the specified radiobearer, identifying information for an associated Enhanced Packet System(EPS) bearer, identifying information for a transmission point that willcarry the specified radio bearer (e.g., whether the specified radiobearer is to be added to the primary transmission point or a secondarytransmission point), identifying information for the UE in thetransmission that will be carrying the specified radio bearer,configuration information on how the specified radio bearer will betransmitted in the transmission point involved (the secondarytransmission point) (i.e., whether or not data for the specified radiobearer is to be split between the primary transmission point and thesecondary transmission point, and if the data is to be split, what newQoS control parameters, such as QCI, ARP, bit rate, and so forth, are tobe used in the primary transmission point), how in-order delivery ofPDCP packets should be performed to combine data from RLC entitiescorresponding to different transmission points, how data retransmissionsshould be handled should a PDCP packet transmission fail, and so forth.

The primary transmission point may send a CoMP Configuration Requestmessage to the UE (block 1034). The CoMP Configuration Request messagemay identify the transmission points involved in the CoMP transmission.The CoMP Configuration Request message may also identify associatedradio bearer and EPS bearer, the identity of the UE with thetransmission points, associated radio bearer configuration parameters,and so on. The configuration parameters for the associated radio bearermay include how in-order delivery of PDCP packets should be performed tocombine data from the RLC entities from the different transmissionpoints, how the UE should respond to missing PDCP packets, and so forth.The primary transmission point may receive a response from the UE.

The primary transmission point may send a CoMP Radio BearerConfiguration Response message to the CoMP controller (block 1036). TheCoMP Radio Bearer Configuration Response message may contain a responsefrom the UE responsive to the CoMP Configuration Complete message.

The primary transmission point may receive a CoMP Radio BearerConfiguration Request message from the CoMP controller (block 1038). TheCoMP Radio Bearer Configuration Request message may indicate that thesetting up or modification of the CoMP transmission configuration iscomplete. The primary transmission point may receive downlink data froma serving gateway (block 1040) and send part of the downlink data to thesecondary transmission point, while sending another part of the downlinkdata to the UE (block 1042).

FIG. 10c illustrates a flow diagram of secondary transmission pointoperations 1050 in setting up or modifying CoMP transmissionconfiguration. Secondary transmission point operations 1050 may beindicative of operations occurring in a secondary transmission point,such as secondary transmission point 815, as the secondary transmissionpoint participates in setting up or modifying a CoMP transmissionconfiguration, such as radio bearer transmission configuration.

Secondary transmission point operations 1050 may begin with thesecondary transmission point receiving a CoMP Configuration Requestmessage (block 1055). The CoMP Configuration Request message may includethe QoS and/or RRM parameters as determined by the CoMP controller. TheQoS and/or RRM parameters may include QoS Class Index (QCI), Allocationand Retention Priority (ARP), bit rate information (what is a guaranteedbit rate and what is a best effort bit rate, as examples), possibleradio resource partitioning (in time and/or frequency domain, forexample), and so on. The secondary transmission point may respond to theCoMP Configuration Request message.

The secondary transmission point may receive a CoMP Radio BearerConfiguration Request message (block 1057). The CoMP Radio BearerConfiguration Request message may include QoS and/or RRM parameters forthe radio bearer. The QoS and/or RRM parameters may includeconfiguration information for RLC entity and MAC entity located at thesecondary transmission point. The secondary transmission point may alsobe provided information regarding if it should provide reports ofpackets with failed delivery attempts and how to do so. The secondarytransmission point may respond to the CoMP Radio Bearer ConfigurationRequest message.

The secondary transmission point may receive downlink data from theprimary transmission point (block 1059) and send the downlink data tothe UE (block 1061).

FIG. 10d illustrates a flow diagram of CoMP controller operations 1075in setting up or modifying a CoMP transmission configuration. CoMPcontroller operations 1075 may be indicative of operations occurring ina CoMP controller, such as CoMP controller 820, as the CoMP controllerparticipates in setting up or modifying a CoMP transmissionconfiguration, such as radio bearer transmission configuration.

CoMP controller operations 1075 may begin with the CoMP controllerreceiving measurements of channel conditions from the primarytransmission point (block 1080). Based on the measurements of channelconditions, the CoMP controller may determine an appropriate CoMPtransmission configuration (e.g., a CoMP mode) to be used, includingsettings of a radio bearer to be used in CoMP transmission, and so on.Settings of the radio bearer may include which transmission points(e.g., primary transmission point and one or more secondary transmissionpoints) may be involved in carrying the radio bearer, as well as QoSand/or Radio Resource Management (RRM) parameters of the radio bearerfrom the involved transmission points.

The CoMP controller may then send a CoMP Configuration Request messageto the secondary transmission point (block 1082). The CoMP ConfigurationRequest message may include the QoS and/or RRM parameters as determinedby the CoMP controller. The QoS and/or RRM parameters may include QoSClass Index (QCI), Allocation and Retention Priority (ARP), bit rateinformation (what is a guaranteed bit rate and what is a best effort bitrate, as examples), possible radio resource partitioning (in time and/orfrequency domain, for example), and so on. The CoMP controller mayreceive a response from the secondary transmission point.

The CoMP controller may send a CoMP Radio Bearer Configuration Requestmessage to the primary transmission point (block 1084). The CoMP RadioBearer Configuration Request message may include identifying informationfor the specified radio bearer, identifying information for anassociated Enhanced Packet System (EPS) bearer, identifying informationfor a transmission point that will carry the specified radio bearer(e.g., whether the specified radio bearer is to be added to the primarytransmission point or the secondary transmission point), identifyinginformation for UE 805 in the transmission that will be carrying thespecified radio bearer, configuration information on how the specifiedradio bearer will be transmitted in the transmission point involved (thesecondary transmission point) (i.e., whether or not data for thespecified radio bearer is to be split between the primary transmissionpoint and the secondary transmission point, and if the data is to besplit, what new QoS control parameters, such as QCI, ARP, bit rate, andso forth, are to be used in the primary transmission point), howin-order delivery of PDCP packets should be performed to combine datafrom RLC entities corresponding to different transmission points, howdata retransmissions should be handled should a PDCP packet transmissionfail, and so forth. The CoMP controller may receive a response from theprimary transmission point.

The CoMP controller may send a CoMP Radio Bearer Configuration Requestmessage to the secondary transmission point (block 1086). The CoMP RadioBearer Configuration Request message may include QoS and/or RRMparameters for the radio bearer. The QoS and/or RRM parameters mayinclude configuration information for RLC entity and MAC entity locatedat secondary transmission point 815. The secondary transmission pointmay also be provided information regarding if it should provide reportsof packets with failed delivery attempts and how to do so. The CoMPcontroller may receive a response from the secondary transmission point.

The CoMP controller may send a CoMP Radio Bearer Configuration Requestmessage to the primary transmission point (block 1088). The CoMP RadioBearer Configuration Request message may inform the primary transmissionpoint that the setting up or modifying of the CoMP transmissionconfiguration is complete.

Since the PDCP packets from the single radio bearer may be independentlysent from geographically separated transmission points, their arrival atthe UE may be in a different sequence from their sequence numberingassigned by the PDCP entity would indicate. Therefore, in-order deliveryof the packets may need to be ensured at the UE. One technique that maybe used to ensure in-order packet delivery is to enhance in-orderdelivery and duplicate detection functionality of the receiving PDCPentity at a UE.

Another technique is to ensure in-order packet delivery at a counterpartof the data splitting interface at the UE between the receiving RLCentities and the receiving PDCP entity. The implementation of in-orderpacket delivery at the interface between the receiving RLC entities andthe receiving PDCP entity may be achieved using a memory, such as abuffer, and some logic.

FIG. 11 illustrates a flow diagram of operations 1100 in re-ordering ofpackets. Operations 1100 may be indicative of operations occurring in aUE as the UE re-orders packets received from different transmissionpoints.

Operations 1100 may begin with the UE receiving packets from thetransmission points (block 1105). Since the packets may be sent fromgeographically separated points but associated with a single radiobearer, the packets may arrive in an order different from their intendedreceiving order. The received packets may then be stored in a memory,such as a buffer (block 1110).

The stored packets may be ordered based on a sequencing number, such asa PDCP sequence number (block 1115). The sequencing number, such as thePDCP sequence number, may be assigned to each of the packets as they areprepared for distribution by the primary transmission point and aredistributed to the secondary transmission points (as well as the primarytransmission point).

A check may be performed to determine if there are any missing packets(block 1120). According to an example embodiment, missing packets may bedetected by scanning the ordered packets and determining if there is adiscontinuity (e.g., a missing sequence number or missing sequencenumbers) in the sequencing number of the ordered packets. Since thepackets have been ordered, the presence of a missing packet may indicatethat there is an out of order packet or packets. As an illustrativeexample, consider an ordered list of packets with PDCP sequence numbers:1, 2, 3, 4, and 5. Since there are only five packets and they are inorder per their PDCP sequence number, there are no missing packets andnone of them are out of order or lost. However, consider an ordered listof packets with PDCP sequence numbers: 6, 7, 8, 10, and 11. Since apacket with PDCP sequence number 9 is absent, it may be considered thatthe packet with PDCP sequence number 9 is out of order and potentiallylost.

If there are no out of order packets in the memory (block 1120), thennone of the packets in the memory are out of order or are lost and thepackets may be provided to a higher network layer entity, such as thePDCP entity for processing (block 1125).

However, since the packets may be arriving from different transmissionpoints, just because a particular packet is out of order does not meanthat the packet is actually lost. A threshold may be used to helpdetermine if the particular packet is actually lost in transmission orsimply delayed because it was transmitted by a different transmissionpoint.

According to an example embodiment, the threshold may be a specifiedamount of time (e.g., as implemented by a timer or a counter) that theUE will wait for the particular packet to arrive before declaring theparticular packet as lost. Alternatively, the threshold may be a numberof packets that is received by the UE after the UE detects that theparticular packet is missing before the UE declares that the particularpacket as lost. The number of packets may be specified specifically fora transmission point. For example, the UE will wait until it hasreceived the specified number of packets from the same transmissionpoint that was expected to transmit the particular packet beforedeclaring the particular packet as lost.

A check may be performed to determine if the particular packet meets thethreshold (block 1130). If the particular packet does not meet thethreshold, then the UE may continue to wait for arrival of theparticular packet, as well as other packets (block 1105). If theparticular packet meets the threshold, then the particular packet may beconsidered to be a lost packet (block 1135) and the UE may optionallyinitiate lost packet recovery (block 1140).

According to an example embodiment, the UE may initiate lost packetrecovery by sending a report to the primary transmission point with thereport indicating that the particular packet has been lost.Alternatively, the UE may send the report to a CoMP controller. The UEmay help to reduce overhead by aggregating a number of lost packets orwaiting for a specified amount of time before sending a report.Furthermore, the UE may send a negative acknowledgement to thetransmission point responsible for transmitting the particular packet.

The UE may return to block 1105 to wait for the arrival of additionalpackets.

Once a PDCP PDU has passed through a data splitting interface, such asdata splitting interface 610, to a transmission point for transmissionto the UE, then the transmission of the PDCP PDU becomes the soleresponsibility of the transmission point. If, for some reason, thepacket does not arrive at the UE, such as due to poor channel condition,high load, etc., the PDCP PDU may be declared lost. Network based and/orUE assisted approaches may be used to help mitigate lost packets.

FIG. 12a illustrates a flow diagram of operations 1200 in a datasplitting interface as the data splitting interface performs networkassisted lost packet mitigation. Operations 1200 may be indicative ofoperations occurring in a data splitting interface, for example, datasplitting interface 610 at a secondary transmission point, as the datasplitting interface assists in detecting and reporting lost and/or errorpackets.

Operations 1200 may begin with the data splitting interface receiving apacket (block 1205). The data splitting interface, located in atransmission point, may receive the packet from the PDCP entity and adata splitting interface, both located in a primary transmission point.The data splitting interface may start a timer (or a counter) to beassociated with the packet to be used in determining if the packet islost in delivery. The timer (or the counter) may make use of a timevalue associated with the packet, which if the packet is not deliveredto a UE before the timer (or the counter) expires, the packet is to bedeemed as having been lost.

The data splitting interface may perform a check to determine if thetimer (or the counter) has expired (block 1209). If the timer (or thecounter) has not expired, the data splitting interface may perform acheck to determine if a positive acknowledgement associated with thepacket has been received (block 1211). In general, the positiveacknowledgement may be an indication that the UE received the packet andwas able to successfully decode the packet. If the positiveacknowledgement has been received for the packet, then the datasplitting interface may deem that the packet has been successfullydelivered to the UE (block 1213) and the timer (or the counter) may bereset.

If the positive acknowledgement has not been received for the packet,the data splitting interface may perform a check to determine if anegative acknowledgement has been received for the packet (block 1215).In general, the negative acknowledgement may be an indication that theUE received the packet and was not able to successfully decode thepacket. If the negative acknowledgement has been received for thepacket, then the data splitting interface may deem that the packet hasbeen received in error by the UE (block 1219) and the data splittinginterface may optionally initiate lost packet recovery (block 1219),which may include sending a lost packet report to the primarytransmission point.

If the timer (or the counter) has expired (block 1209), then the datasplitting interface may deem that the packet has been lost (block 1221)and the data splitting interface may optionally initiate lost packetrecovery (block 1223), which may include sending a lost packet report tothe primary transmission point.

FIG. 12b illustrates a flow diagram of operations 1230 in a datasplitting interface of a primary transmission point as the datasplitting interface recovers and/or redistributes lost and/or errorpackets in lost packet mitigation, wherein the lost packet mitigationmay be in the form of network assisted and/or UE assisted lost packetmitigation. Operations 1230 may be indicative of operations occurring ina data splitting interface as the data splitting interface assists inrecovering from lost packets and redistributing packets for potentialretransmission.

Operations 1230 may begin with the data splitting interface distributinga packet to a transmission point (block 1235). As discussed previously,the data splitting interface may distribute the packet to any of Ntransmission points based on a distribution.

The data splitting interface may then perform a check to determine if ithas received a lost packet report from one of the transmission points orfrom a UE (block 1237). According to an example embodiment, thetransmission points or UEs may be configured to provide a lost packetreport upon the detection of a lost packet, upon detection of aspecified number of lost packets, periodically provide a lost packetreport even if no lost packets have occurred, or so forth. If the datasplitting interface has not received a lost packet report, then it mayreturn to block 1235 to distribute additional packets.

If the data splitting interface has received a lost packet reportindicating the lost of one or more packets, then the data splittinginterface may re-distribute the lost packet(s) to a differenttransmission point (or transmission points) (block 1239). The datasplitting interface may alter the distribution so that the number ofpackets distributed to a transmission point that is a source of the lostpacket may be reduced, while the number of packets distributed toanother transmission point that is not having lost packets may beincreased, as examples. According to an example embodiment, the datasplitting interface may distribute the lost packet based on a number ofconsiderations, such as lost packet rate for the various transmissionpoints, available resources at the various transmission points,transmission point load, and so on.

Furthermore, the data splitting interface may consider re-distributingthe lost packet to the transmission point that reported the lost packetif the transmission point has not lost a large number of packets, thetransmission point has a historically good lost packet rate, and so on.

FIG. 12C illustrates a flow diagram of operations 1260 in UE assistedlost packet mitigation. Operations 1260 may be indicative of operationsoccurring in a UE as the UE assists in detecting and recovering fromlost packets.

Operations 1260 may begin with the UE receiving a packet (block 1265).The UE may perform a check to determine if a missing packet criterionhas been met (block 1267). An example of a missing packet criterion mayinclude a missing packet in a re-ordering buffer for a specified amountof time or a specified number of packet receptions, and so forth. If themissing packet criterion is met, then the UE may report the missingpacket(s) to the primary transmission point, the CoMP controller, orboth (block 1269).

Alternatively, instead of immediately reporting each missing packet, theUE may wait a specified amount of time before reporting the missingpacket. Alternatively, the UE may wait until there is a specified numberof missing packets before reporting the missing packets. The UE mayaggregate the information about the missing packets.

Alternatively, the UE may be configured to provide a status report onmissing packets, even if there are no missing packets at the time of thestatus report. A period for the status reports or a trigger fortriggering a status report may be specified by a primary transmissionpoint or a CoMP controller.

FIG. 13 provides an illustration of a transmission point 1300.Transmission point 1300 may be an implementation of a communicationscontroller, such as an eNB, a BS, a cell, a RRH, or so on. Transmissionpoint 1300 may be used to implement various ones of the embodimentsdiscussed herein. As shown in FIG. 13, a transmitter 1305 is configuredto transmit information and a receiver 1310 is configured to receiveinformation. Transmitter 1305 and receiver 1310 may have a wirelessinterface, a wireline interface, or a combination thereof. In practice,transmitter 1305 and receiver 1310 might be implemented in a single unitof hardware.

A network protocol processing unit 1320 is configured to provideprocessing of packets at one or more network protocol layers. As anexample, network protocol processing unit 1320 may include a PDCPentity, a RLC entity, a MAC entity, or so on. Depending on radio bearerconfiguration, not every entity is available for processing of packets.Consider a situation wherein a single radio bearer is split betweenmultiple transmission points. In such a situation, a RLC entity may beavailable, but a PDCP entity may not be available depending on theconfiguration of transmission point 1300 (e.g., a primary transmissionpoint versus a secondary transmission point).

A data splitting unit 1322 is configured to handle data splittingrelated functions when sending a single radio bearer over multipletransmission point. For example, for a primary transmission point, datasplitting unit 1322 may split packets of a single radio bearer fordistribution to transmission points involved with the single radiobearer. Data splitting unit 1322 is configured to distribute the packetsto the transmission points based on a desired distribution that may bebased on considerations such as transmission point capability,transmission point load, channel quality, and so forth. Data splittingunit 1322 may determine its own desired distribution as well as otheraspects of CoMP transmission or receive them from the CoMP controller ordetermine them in conjunction with the CoMP controller. Data splittingunit 1322 may also receive feedback from other network entitiesregarding the delivery status of individual packets, and initiate packetredistribution/loss discovery when necessary. For a secondarytransmission point, data splitting unit 1322 may receive packets from aprimary and provide feedback to the primary when necessary. A memory1330 is configured to store packets for transmission, CoMP transmissionconfiguration information, and so forth.

The elements of transmission point 1300 may be implemented as specifichardware logic blocks. In an alternative, the elements of transmissionpoint 1300 may be implemented as software executing in a processor,microprocessor, digital signal processor, controller, applicationspecific integrated circuit, or so on. In yet another alternative, theelements of transmission point 1300 may be implemented as a combinationof software and/or hardware.

As an example, transmitter 1305 and receiver 1310 may be implemented asa specific hardware block, while network protocol processing unit 1320,and data splitting unit 1322 may be software modules executing in aprocessor 1315, such as a microprocessor, a digital signal processor, acustom circuit, or a custom compiled logic array of a field programmablelogic array.

FIG. 14 provides an illustration of a CoMP controller 1400. CoMPcontroller 1400 may be an implementation of a network entity intended toprovide control of CoMP transmissions occurring in a communicationssystem. Alternatively, CoMP controller 1400 may be implemented as alogical entity that is part of an existing network entity, such as acommunications controller, a gateway, an eNB, or so on, in thecommunications system. CoMP controller 1400 may be used to implementvarious ones of the embodiments discussed herein. As shown in FIG. 14, atransmitter 1405 is configured to transmit information and a receiver1410 is configured to receive information. Transmitter 1405 and receiver1410 may have a wireless interface, a wireline interface, or acombination thereof. In practice, transmitter 1405 and receiver 1410might be implemented in a single unit of hardware.

A channel condition processing unit 1420 is configured to processchannel condition reports from UEs. For example, channel conditionreports from UEs may provide indications of the condition of channels toand from the UE as well as the condition of communications controllersnear or detectable by the UE. Channel condition processing unit 1420 maycombine the channel condition reports from multiple sources (such asother UEs) to obtain a picture of the UE's operating condition.

A decision making unit 1422 is configured to make a decision on the UE'sCoMP transmission configuration, such as a radio bearer configurationfor CoMP transmission, based on the operating condition of the UE. As anexample, if the operating condition of the UE is high, the UE's CoMPtransmission configuration may be adjusted to increase an overallperformance of the CoMP transmission to the UE. Similarly, if theoperating condition of the UE is low, the UE's CoMP transmissionconfiguration may be adjusted to decrease the overall performance of theCoMP transmission to the UE to achieve better error performance.

A modifying unit 1424 is configured to generate messaging to implementchanges in the CoMP transmission configuration of the UE. The messagingmay be transmitted to the various members of the UE's CoMP cooperatingset to change the CoMP transmission configuration. A memory 1430 isconfigured to store packets for transmission, CoMP transmissionconfiguration information, radio bearer configuration information, andso forth.

The elements of CoMP controller 1400 may be implemented as specifichardware logic blocks. In an alternative, the elements of CoMPcontroller 1400 may be implemented as software executing in a processor,microprocessor, digital signal processor, controller, applicationspecific integrated circuit, or so on. In yet another alternative, theelements of CoMP controller 1400 may be implemented as a combination ofsoftware and/or hardware.

As an example, transmitter 1405 and receiver 1410 may be implemented asa specific hardware block, while channel condition processing unit 1420,decision making unit 1422, and modifying unit 1424 may be softwaremodules executing in a processor 1415, such as a microprocessor, adigital signal processor, a custom circuit, or a custom compiled logicarray of a field programmable logic array.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for detecting lost packets, the methodcomprising: initiating a timer for a received packet at a receivingtransmission point, wherein the timer is set according to a time valueassociated with the received packet; determining that a delivery of thereceived packet has failed according to the timer elapsing; andtransmitting a lost packet report to a primary transmission point thatdistributed the received packet to the receiving transmission point. 2.The method of claim 1, wherein determining that the delivery of thereceived packet has failed comprises determining that the timer haselapsed prior to receiving a positive acknowledgement for the receivedpacket.
 3. The method of claim 1, wherein determining that delivery ofthe received packet has failed further comprises receiving a negativeacknowledgement for the received packet.
 4. The method of claim 1,wherein transmitting the lost packet report comprises transmitting anaggregation of information related to failed packet deliveries for aspecified time interval.
 5. A method for transmitting information by aprimary transmission point, the method comprising: determining adistribution for allocating packets in a plurality of packets to Ntransmission points in a multiple point cooperating set, where N is aninteger value greater than or equal to two, wherein the primarytransmission point is one of the N transmission points; allocating thepackets in the plurality of packets to the N transmission points fortransmission to a user equipment in accordance with the distribution,wherein the plurality of packets to be transmitted by the N transmissionpoints belong to a single radio bearer; sending the allocated packets tothe N transmission points; and transmitting primary packets allocated tothe primary transmission point to the user equipment.
 6. The method ofclaim 5, wherein determining the distribution comprises receiving thedistribution from a controller.
 7. The method of claim 5, whereindetermining the distribution comprises determining the distributionaccording to a distribution criteria.
 8. The method of claim 7, whereinthe distribution criteria comprises a capability of each of the Ntransmission points, a channel condition at each of the N transmissionpoints, a load of each of the N transmission points, a lost packethistory of each of the N transmission points, or a combination thereof.9. The method of claim 5, further comprising receiving a notification ofa lost packet previously allocated to a first transmission point, andwherein allocating the packets further comprises: altering thedistribution to account for the lost packet by the first transmissionpoint; and redistributing the lost packet according to the altereddistribution.
 10. The method of claim 9, wherein the distribution forthe first transmission point is decreased to reduce a number of packetsdistributed to the first transmission point.
 11. The method of claim 9,wherein allocating packets further comprises increasing the distributionfor a second transmission point to increase a number of packetsallocated to the second transmission point.
 12. The method of claim 9,wherein the notification is received from the first transmission point.13. The method of claim 9, wherein the notification is received from theuser equipment.
 14. A primary transmission point comprising: a processorconfigured to determine a distribution for allocating packets in aplurality of packets to N transmission points in a multiple pointcooperating set, where N is an integer value greater than or equal totwo, wherein the primary transmission point is one of the N transmissionpoints, and configured to allocate the packets in the plurality ofpackets to the N transmission points for transmission to a userequipment in accordance with the distribution, wherein the plurality ofpackets to be transmitted by the N transmission points belong to asingle radio bearer; and a transmitter coupled to the processor, thetransmitter configured to send the allocated packets to the Ntransmission points, and to transmit primary packets allocated to theprimary transmission point to the user equipment.
 15. The primarytransmission point of claim 14, wherein the distribution is according toa capability of each of the N transmission points, a channel conditionat each of the N transmission points, a load of each of the Ntransmission points, a lost packet history of each of the N transmissionpoints, or a combination thereof.
 16. The primary transmission point ofclaim 14, further comprising a receiver configured to receive anotification of a lost packet previously allocated to a firsttransmission point, and wherein the processor is configured to alter thedistribution for the first transmission point.
 17. The primarytransmission point of claim 16, wherein the processor is configured toalter the distribution to account for the lost packet by the firsttransmission point, and to redistribute the lost packet according to thealtered distribution.